Method of and apparatus for forming venetian blind slats



Feb. 21,1

7 A. B. WILSON IETHOD OF AND APPARATUS FOR FORMING VENETIAN BLIND SLATSFiled Feb. 9, 1942 en m es its 2?, 1945 stares PATENT OFFICE THUR-0FAPPMATUS FOR FORM- mo VENETIAN' BLIND SLA'ES' I Allen B. Wilson,Evanstcn, Ill, or to Acme Steel (Company, @hiccso, lit, a corporation oiHlinois Application February 9, 1M2, No. $30,612

ici. 1532) 12 Claims,

curved or other non-planar cross section. The.

present invention is an improvement upon that described and claimed inthe copending application of Joseph L. Hunter. Serial No. 279,391, filedJune 19, 15, 39,

in order that's. Venetian blind slat may have the required stiffnesswhen it is formed of thin metal, it is necessary that it have a curvedor other non-planar crcss section, and strips having this characteristicand alsohaving parallel edges may be used advantageously for otherpurposes. it has been found that commercial strip steel, as it comesfrom the mills, is not well adapted for the commercial manufacture ofVenetian blind slats because it is not perfectly fiat and has variationsin temper and gauge distributed more or less throughout its entirelength and area, so that attempts to convert a commercial strip into aform having a curved or other non-planar cross section by any of theusual rolling and bending tions of the strip to be stretchedlongitudinally to substantially the same extent that the intermedi ateportion was stretched in the first stage of the process. The elongatedstrip than emerges from the second stage of the process as a straightmember having a bowed cross section and parallel longitudinal edges.

In the said application of Joseph L. Hunter, there is illustrated anddescribed a form of apparatus for carrying out the two=stage processabove termediate portion is stretched by passing it end-= wise over acrowned roller while under tension sufilcient to sheet the stretching ofthe desired portion.

The present invention is based upon the discovery that theabove-described two-stage method may be practiced without the use or crysupports in advance of and following the forming rolls which impart thetransverse curvature to the strip and that this simplification may beaccomplished by employing in the first stage the relatively inclinedsets of blocks, disclosed in said application of Joseph L. Hunter. andso adiustmg the relative inclination of the successive sets 0! blocks asto cause to be effected in the first stage nallyby a stress exceedingthe elastic limit of the metal, the degree of tension exerted upon themetal being such that the irregularities in the portion subjected to thestretching operation are removed so that all parts of this intermediate4 portion would be under compression if the tension were released.Having thereby established a knowncondition in the metal strip,asdistlngulshed from the uncertain and unknown condition existing in thecommercial material at the place of bending, thereby causing the lateralporthat precise relativeelongation of different laterally displacedparts of the strip which will have the efi'ect of causing the strip toemergefrom the I'ormifig rolls of the second stage as a. member-oi bowedcross section and parallel edges which is either straighter .01 anyother desired longitudi nal shape. By this improved method the strippasses directly from the first stage to the second stage an toerelativestretching of the intermediate portion and the lateral edgeportions is so regulated in the first stage that the strip will coactwith the forming rolls and assume a, curved cross section'and astraighttorm. By this improvement both the apparatusand the method aresimplified and the apparatus ofthe first stage may be readily adjustedwhile the stretching and Liorming are in progress in order to cause thefinal product to have the desired form. Other oblects of the inventionrelate to various features or construction -and arrangement of theapparatus and to details of the method which will appear morefullyhereinafter.

The nature of the invention will be understood from 'the followingspecification taken with the accompanying drawing .in which one exampleof thedmprovd method and one form of the improved apparatus areillustrated. In the drawing,

Figure 1 shows a partial side elevation of the improved apparatus of thepresent invention;

view of a portion of one of the completed slats.

As illustrated in the drawing, the strip metal employed in the practiceof the present invention, which metal may preferably be thin steel whichis hard and resilient, is wound in a coil supplied from a reel 8fromwhich it passes around an idler roller and then around a frictiondrag roller l0 having an outer surface of rubber or the like andprovided with an adjusting device i iflwhich may be regulated forvarying the resistance to the rotation of the roller for retarding themovement of the metal strip II as it is unwound from the coil. Thismetal strip is withdrawn from the reel 8 under tension and is movedthrough confining passages in two sets of die blocks l2 and I3 and,after emerging from the second set of die blocks, the strip passesbetween forming roll H and It provided with complementary concave andconvex peripheral surfaces, respectively, which may conform to the arcof a circle, and which bend the strip transversely as it passestherethrough in a continuous operation. The forming rolls I4 and itmaybe relied upon to feed the strip through the apparatus and maintaintension therein, in which case the roll l5 will have a peripheralsurface of rubber or the like, or the strip may be drawn through therolls l4 and II, as well as through the die blocks l2 and It, by powerdriven drive rollers 29 and 30 which maintain suillcient tension in thestrip to bring about the stretching of the metal in the mannerhereinafter referred to.

The set of die'blocks l2 comprises an upper block I! and a lower blockI! which are provided with complementary concave and convex surfaces,respectively, extending transversely thereof to form between them aconfining passage of arcuate cross section concaved downwardly and ofsubstantially the same widthas the strip, the

' height of the passage being only slightly greater than the thicknessof the metal strip to be treated so that the upper and lower sides ofthe strip are engaged by the blocks l2 and I2, respectively,

during the passage .of the strip th'erethrough. The v blocks i2 and l2are secured together and maintained in the desired spaced relation byside plates l2 which are'secured to the blocks by screw If. Thesideplaies W are provided with rearwardly extending arms I! havingrotatably mounted be-' tween them a guide roller It which 'is'adapted tocontactwiththeundersideofthestrip II asitis withdrawnfrom thereelsothatthestrlpiscaused' tofollowanxedpa'thasitentersoneofthedieblock; it, regardless of theangular position of thisbiock.

v The otherset of die blocks lI-comprises an upsecured together arcuatecross section concaved downwardly and and a lower block it" which areand spaced apart by side plates il secured in position by screws It.These die blocks It and It are also provided with opposed concave andconvex surfaces, respectively, which form between them a restrictedpassage of per block, I3

formed by radii having a common center, these surfaces preferably havingthe same width and curvature and the same spaced relation as thecorresponding surfaces formed on the die blocks II. The side plates Ware provided with rearwardly extending ears I! which project betweensimilar ears I! formed on the side plates 12. These ears are pivotallyconnected by pins l1 and are adapted to permit the die blocks I! to beswung angularly with respect to the die blocks It so that the angularityof the restricted passages throiigh the two sets of die blocks may beregulate The die blocks I3 are adapted to be secured upon a fixedsupport, not illustrated, and the side offset upwardly and rearwardly toprovide a support for the rear portion of the die blocks II. For thispurpose, the side plates I! are provided with another pair of upwardlyextending ears II having a pivotal engagement by means of the pin IIwith an eye-bolt 2|. This bolt extends upwardly through an elongatedslot it formed in the bar 18 and is engaged beneath the bar by a washer22 and a wing nut 23. On the upper side of the bar, the bolt is engagedby a washer 24 and a wing nut 25. It will be apparent that byadjustingthe wing nuts 23 and II the rear end of the set of die blocks 12 may beraised or lowered in order to change the angularity of the passagebetween the blocks l2 and l2 with respecttto the passage between theblocks It and II". The cylindrical roller It which engages the undersideof the commercial strip material being withdrawn from the reel 8 isadapted to maintain the strip in alignment with the passage between theblocks I! and Ill as it enters that passage, regardless of the angularpositions of these blocks.

Due to the curvature of the passages between the die blocks, it will beapparent that the intermedlate'portion of the part I I of the stripwhich is passing through the gap between the two die blocks must travela longer path than the edge portions which re nearer to the pivot I!whichconnects the two sets of blocks. Inasmuch as all parts of the stripmust travel at the same speed,

this difference in the distance throughwhich different parts of thestrip must pass, in going from one set or blocks to the other, resultsin a permanent stretching or elongation of the intermediate portion ofthe strip. The width of the portion of the strip which is thus stretchedand the relative extents of the stretching of dlil'erent portions of thestrip which are laterally displaced from each other may be regulated byadlusting the wing nuts 23 and II and thereby effecting a correspondingvadiustment of the longitudinal inclination of the-passage between thedie blocks I! with respect to the corresponding passage through the dieblocks ll. l'ior example,-by increasing this angle, as a result oflowering the rear end'ofthe die blocks II, the stretching or permanentelongation of the intermediate portion of strip may be increased camerawith respect to the edge portions. By suitably adjusting the blocks thepermanent stretching which is effected in the blocks l2 and It may becaused to extend throughout a major portion of the width of the stripalthough varying in magnitude in different laterally displaced parts ofthe strip. In some cases the commercial strip mate rial may have itscenter portion elongated as it comes from the supply reel and, in thatevent, it may he desirable to effect some permanent stretching oi theedge portions of the strip as it passes through the sets of blocks 52and it. This may be done by raising the blocks 92, as indicated dotmdlines in Fig. 2, thus causing the edge nortions oi the strip to passthrough a longer gap than the center portion in traveling from one setof blocks to the other.

After emerging from the die blocks 52, the strip is carried through theforming rollers id and it which are secured on shafts 2? and 2%,respecvely, these shafts being power driven in the ectlons indicated bythe arrows. The laterally curved peripheral surfaces l5 and 85 of the iud, since the resilient metal dency to spring sacs; partially toward waslosing thus hent transverse curs-a he peripheral is metal will incl lainp when a number oi then-c are usual manner a Vane-- the rolls 3& and iiimoving thestrip and main degree of tension therein,

as well throush the hlcchs cctu driving rolls sa ce opposite sides oithe strip ve cylindrical peripheral suriaces. are preferably iorncecl oisteel after passing around snh= cne hali oi the peripheral surface ofreversal and passed around the r portion oi the roll lid "with which itis main in close contact by the pressure roll 32 peripheral portionformed or rubber or e Lie. The rolls 2i? and 38 are of the same arnetersand are power driven, being geared tonether so that their peripheralportions travel at same speed. in pacing around the rolls as sl-awnunder tension through emerges from the of curved cross section which arerelatively iii--v stood that the apparatus and 80 the concave strip istemporarily flattened but promptly resumes its normal transversecurvature due to the resilience of the metal.

If, during the operation of the apparatus, it be found that the portionH is not straight, or doesnot have any other longitudinal shape which isdesired, this may be corrected by adjusting the wing nuts 23 and 25 toefiect a corresponding adjustment of the angularity or the die blocks itwith respect to the die blocks it, since it has been discovered that bysuitably regulating the relative longitudinal stretching of differentlaterally displaced portions of the strip, as it passes through the dieblocks l2 and E3, the strip may be caused to assume any desiredlongitudinal shape, within reasonable limits, when it emerges from theforming rolls as and it. The concavity of the passages through the diehloclrs l2 and it and the concavity of the passage between the formingrollers it and i5 are both directed downwardly and the relativelongitudinal singularity of the passages through the die blocks l2 andi3 is also directed downwardly. The passages through the die blocks arepreferably straight longitudinally although they might have other shapeswith a similar effect. The major porticn oi the longitudinal stretching,by which the inequalities in the internal stresses in the metal areremoved in the final product, may he efiected largely or Wholly by thedie blocks but, in general, there will be some longitudinal stretchingof the lateral edge portions. of the strip as it passes through theforming rolls by reason of the fact that, due to theincreased concavityof the strip g at the place Where it contacts the forming rolls,

all carts the strip will have been stretched longr dinally tosubstantially the same degree.

Although one form of the improved apparatus and one example of theimproved method have been illustrated and described, will he under evarious forms and that the method may lie-p1 enticed in various wayswithout departing from the scope of the appended claims.

claim:

1. The method of forming metal strip having a predetermined longitudinalcho ce and a non planar cross section, which consists in the stripthrough a plurality of confining passages cllnecl longitudinally of thestrip, then bending the strip transversely to approximate the do sirednon-pia. or cross section, maintaining longitudinal tension in the stripwhile it is passing through said passages and while it is being benttransversely, and adjusting the relative inclination of said passagesand thereby regulating the longitudinal shape of the product whichfollows said transverse bending.

2. The method of forming in a continuous process a straight metal striphaving a. curved cross section, which consists in passing the stripunder longitudinal tension through successive confining passagesof'curved lateral cross section which are relatively inclinedlongitudinally with respect to each other, then immediately confiningthe moving strip and bending it transversely while moving it endwise andmaintaining said longitudinal tension therein, and adjusting therelative inclination of said passages and thereby causing the strip toemerge from the transverse bending operation as a straight strip havinga curved cross section.

3. The combination in apparatus for forming a metal strip having apredetermined longitudinal shape and a non-planar cross section, of aplurality of sets of die blocks each having a longitudinal stripconfining passage therethrough which is transversely curved, saidpassages in said die blocks being-relatively inclined longitudinally,forming rolls having non-planar p eripheral surfaces adapted to receivea metal strip between them, means for pulling a metal strip endwisethrough the passages of said die blocks and then between said formingrolls, and means for adjusting the relative inclination of said sets ofdie blocks and thereby causing the metal strip to emerge from saidforming rolls with the desired longitudinal shape.

4. The combination in apparatus for forming a metal strip having apredetermined longitudinal shape and a non-planar cross section, of aplurality of sets of die blocks each having a longitudinal stripconfining passa e therethrough which is transversely curved, saidpassages in said die blocks being relatively inclined longitudinally,forming rolls having non-planar peripheral sur-' faces adapted to bendthe strip transversely and to pull it through said blocks, and means foradjusting the relative inclination of said blocks and thereby regulatingthe longitudinal stretching of the metal between successive die blocksand causing the metal strip to emerge from said forming rolls with thedesired longitudinal shape.

5. The combination in apparatus for forming a metal strip having apredetermined longitudinal shape and a non-planar cross section, of aplurality of sets of die blocks each having a longitudinal passagetherethrough which is transversely curved, said passages in said dieblocks being relatively inclined longitudinally and havinga width andheight substantially equal to the width and thickness of said strip,forming rolls having non-planar peripheral surfaces adapted to bend thestrip transversely and to pull it through said blocks, means foradjusting the relative inclinationoi' said blocks and thereby causingthe metal to emerge from said forming rolls withthe desired longitudinalshape, and

means for causing the metal strip to enter the passage of the first dieblocks at the same angle with respect to said first die blocks in allrelative positions of the sets of die blocks.

6. The combination in apparatus for forming a metal strip having apredetermined longitudinal shape and a non-planar cross section, of aplurality of sets of die blocks each having alongitudinal passagetherethrough which is trans versel curved, said passages in said dieblocks being relatively inclined longitudinally, and hav- 7 ing a widthand height substantially equal to the width and thickness of said strip,iormlng rolls having non-planar peripheralsuriaoes adapted to receive ametal strip between them, means for pulling a metal strip endwisethrough the passage of said die blocksand then between said formingrolls, means for adjusting therebtive inclination of said sets oi dieblocks and thereby causing the metal strip to emerge from said formingrolls with :the desired longitudinalshapasadmeanstorcauslnsthemetslstriptoenterthepassageoitheflrstdiebloeksetthe same angle with respect to saidiirst die in all relative angular positions of the sets of die blocks.

'7. The combination in apparatus for forming a metal strip having apredetermined longitudinal shape and a non-planar cross section, of aplurality oi sets of die blocks each having a longitudinal passagetherethrough which is transversel curved, said passages in said dieblocks being relatively inclined longitudinally, forming rolls havingnon-planar peripheral surfaces adapted to receive a metal strip betweenthem, means for pulling a metal strip endwise through the passages ofsaid die blocks and then between said forming rolls, means for adjustingthe rela tive inclination of said sets of die blocks and thereby causingthe metal strip to emerge from said forming rolls with the desiredlongitudinal shape, and a roller carried by the first set of die blocksand movable therewith for supporting the metal strip in advance or saiddie blocks.

8. The combination in apparatus for forming a metal strip having apredetermined longitudinal shape and a non-planar cross section, or aplurality of sets of die blocks having longitudinal metal strip inadvance of that set of die blocks.

9. The combination in apparatus for forming a metal strip having apredetermined longitudinal shape and a non-planar cross section, of aplurality of sets of die blocks having longitudinal confining passages,therethrough which are of non-planar cross section and which arerelatively inclined in adjacent sets of die blocks, means or movingendwise through said passages a long metal strip which is initiallysubstantially flat, means ior supporting one set of die blocks from theadjacent set, means for adjusting said one set of die blocks angularlywith respect to said adjacent set through a suilicient range to reversethe relativednclination of said passages, and

means movable with said one set of die blocks for causing said metalstrip to enter the Dassm oi said one set of die blocks at the same anglein all relative posltions'of said one set or die blocks. Y

10. The method of forming in a continuous process a straight metal striphaving a curved cross section, which consists in passing the strip underlongitudinal tension through successive confining passages of curvedcross section which as I passes from were! said passages to the" arelocated in proximity to each other and which are relatively inclinedlongitudinally, preventing transverse displacement or the strip duringits travel through said passages, then immediately confining the movingstrip and bending it transversely while moving it endwise andmaintaining said longitudinal tension therein, and adjusting therelative inclination of said passages and thereby,- regulating thelongitudinal stretching of dilerent laterally displaced portions 0! thestrip other and causing tbd strip to emerge from the transverse bendinghsvingseurvederossseetion.

operation sea straight strip tion, which consists in moving asubstantially flat strip endwise and continuously curving advancingportions of the strip transversely and thereby stressing it within itselastic limit while bending the transversely curved portion of the striplongitudinally during its movement and thereby causing one part of thestrip to be elongated with respect to other laterally displaced partsthereof, then bending the strip transversely and thereby stressing itbeyond its elastic limit and confining it to a non-planar cross section,and adjusting the degree of said longitudinal bending of the strip andthereby regulating the longitudinal shape of the final product.

12. Themethod of forming in a continuous process a straight metal striphaving a curved cross section, comprising a first stage which consistsin curving a substantially flat metal strip transversely, and moving itendwise along a transversely curved and longitudinally bent path andthereby effecting the elongation of the intermediate portions of thestrip with respect to the lateral edge portions thereof, a second stagewhich consists in bending the strip transversely and moving it endwise,and thestep of regulating the relative elongation of the intermediateportions and the lateral edge portions of the strip in said first stageand thereby determining the longitudinal shape of the strip emergingfrom said second stage.

ALLEN B. WILSON.

